Syringe



Jan. 26, 1943. 9 B. DQUGLAS 2,309,502

SYR ING E Filed Dec. 1e, 1940 s sheets-sheet 1 l Jan- 26, 1943- BQDOUGLAS f 2,309,502

y ysammler:

Filed Dec. 1e, 1940 v 3 Sheets-Sheet 2 r v A Patented Jan. Z6, 1943 UNITED TS PATENT QFFICE 10 Claims.

This invention relates to syringes and more particularly to syringes of the type which may be used for injecting under pressure or aspirating fluids of all kinds.

It is an important object of this invention to provide an 'improved syringe construction having means for automatically injecting or aspirating fluids, and additional means for manually controlling or braking the injecting or asp-irating means whereby extremely accurate results may be obtained.

A further object is to provide, in a syringe of novel structure, brake controlling means so arranged that operat'ion thereof will have no tendency to dislodge the needle of the syringe.

A further object of this invention is to provide a hypodermic syringe adapted for automatically delivering local anaesthetics such as novacaine or other drugs with sufficient force through a needle so as to result in an extremely efcient injection and to provide means controlling the force and amount of the fluid injected.

A further object is to provide a hypodermic syringe adapted to automatically aspirate fluids through a needle or nozzle and to provide means controlling the speed and amount of the uid aspirated.

A further object is to provide an automatically operated hypodermc syringe having interchangeable spring seating means in o-rder that either tension or compression spring means, or a combination thereof, may be used.

A further object is to provide a hypodermic syringe constructed and arranged to inject or aspirate predetermined amounts of fluid successively wherein the predetermined amounts may be varied.

A further object is to provide a hypodermic syringe of novel construction including means for injecting or aspirating predetermined amounts of fluid successively and additional means for accurately controlling the speed with which such iiuid is injected or aspirated.

A further object is to provide a hypodermic syringe of novel construction including means for injecting or aspirating predetermined amounts of fluid successively and means for arresting the delivery of such predetermined amounts either before or after such delivery has begun.

Other objects and advantages of the invention will become apparent during the course of the following description.

In the drawings I have shown several embodiments of the invention. In this showing:

Figure 1 is a perspective View of the syringe,

Figure 2 is a central longitudinal sectional view thereof, parts being shown in elevation,

Figure 3 is an elevation of the piston rod assembly in partially assembled relationship,

Figure 4 is a left end elevation of the cap -of the syringe,

Figure 5 is a section ure 2,

Figure 6 is a similar view taken on line 6--6 of Figure 2,

Figure '7 is an elevation of a spring and its seating means, the parts being shown separated,

Figure '7a is a fragmentary sectional View vof a tension spring and its seating means, parts being shown in elevation,

Figure 8 is a side elevation of a modification of the invention,

Figure 9 is a section taken on line 9-9 of Figure 8,

Figure 10 is an enlarged fragmentary side elevation of another modification of the invention,

Figure 11 is an end view thereof, a portion being shown in section,

Figure 12 is a fragmentary section taken on line I2-I2 of Figure 11,

Figure 13 is a fragmentary sectional view of another modification of my invention,

Figure 14 is a view partly in elevation and partly in section of another modification of the invention,

Figure 15 is an end view thereof in elevation,

Figure 16 is a section taken on line IS-l of Figure 14,

Figure 17 is a fragmentary side elevation of another modification of my invention,

Figure 18 is a section taken on the line l3l0 of Figure 17,

Figure 19 is a another modication of Figure 20 is a section of Figure 19,

Figure 21 is an enlarged fragmentary perspective view of the invention in partially assembled relationship taken on the line 2i-2I of Figure 19,

Figure 22 is an enlarged fragmentary section taken on the line 22-22 of Figure 19, parts being shown in plan, and,

Figure 23 is an enlarged section taken on the line 23--23 of Figure 19.

Referring to the drawings, the numeral I0 designates the glass barrel of the syringe which is provided at one end with an externally threaded taken on line 5-5 of Figfragmentary side elevation of my invention, taken on the line 29--20 boss II having an axial opening therethrough, the other end of the barrel being open and having an annular flange I2 for a purpose which will become apparent. An internally threaded member I3 having a centrally located opening I9 extending axially therein is secured to the boss II at one end and a hypodermic needle I5 is screwthreadedly or otherwise connected to the other end of the member I3. It will be seen that the openings through the needle I5, member I3, and boss II form a continuous passage for the flow of uid therethrough. It is apparent that any type of needle or nozzle may be substituted for needle I 5.

The syringe is provided with an internally threaded metallic cap member I9 of substantial thickness (as clearly shown in Figure 2) in which is bored an axially extending opening I1 to provide a bearing for a piston rod I8. The metallic cap member I6 is also bored to provide a transverse opening I9 for a brake rod 29 mounted to rock therein. As will be clearly seen in Figures 2 and 5, opening I9 extends partially into and transversely across opening I1 for a purpose to be described. Centrally of its length the brake rod 29 is cut transversely to form an arcuate notch 2| to receive a portion of the piston rod I 8 when the notch 2| is turned in a position parallel to the piston rod I8. It will be obvious that if brake rod 29 is rotated slightly in the opening I9 the sides of the notch 2| will bind against the piston rod I8 in such manner as to prevent free sliding of the piston rod I8 through the opening I1. If desired the brake rod 29 may be eccentric in cross-section to secure an equivalent braking action when it is rotated or a brake lever may be mounted to rotate on a pin in a vertical slot (Figure 19) in the top of the cap member I6 so that one extremity thereof bears directly on shaft I8 under the action of suitable spring means.

Rigidly secured or keyed to the extremities of the brake rod 29 by means of screws 29 is a brake control handle 22 which is adapted by means of thumb pressure at 23 to cause brake rod 2U to rock in the supporting opening I9. When the parts are in the position shown in Figure 2 the control handle 22 is in its full braking position, that is the sides of the notch 2| on brake rod 29 are exerting the maximum pressure against the piston rod I8. The control handle 22 is retained in its full braking position by suitable spring means such as a leaf spring 24 suitable mounted on the annular surface of the cap member I5 and strongly engaging the f under portion of member 23 to urge the same in a counterclockwise direction together with the brake rod 29 in the opening I9. It will thus become apparent that downward pressure by the thumb upon member 23 acts to rotate brake rod in a clockwise direction so as to permit piston rod I8 to slide freely through the opening I1 as the sides of the notch 2| are no longer urged as a brake against the piston rod I The various elements of the piston rod I9 are clearly shown in Figure 3. A metallic ring or handle 26 is screwthreadedly connected to piston rod I8 and may be secured thereto by a lock nut 21. A member 29 is screwthreadedly connected to the other end of the piston rod I8 and to a piston 3| and includes a swivel joint 39 in order to prevent any side stress developing between the piston 3l and the glass barrel I9 of the syringe during operation thereof. A washer 33 is also loosely mounted on member 29 to the right (Figure 3) of a pin 34. The piston SI lits very snugly within the glass barrel I9 so as to prevent any leakage past the piston under any normal conditions of pressure or suction.

A spring seat 31 (Figures 2, 3 and 7) having an axial opening therethrough is adapted to be placed over piston rod I8 and abuts the internal surface of cap member I6. Two eyelets 35 are screwed into the cap I 6 adjacent the opening I1, for a purpose to be described, and project through diametrically opposite notches 39 which are provided in the periphery of spring seat 31 (Figure 6). A compression spring seat 38 also having an axial opening therethrough is mounted on the member 29 of the piston rod VI8 and abuts the pin 39. A compression spring 39 or compressible rubber tubing is slipped over piston rod I 8 and securely confined between its seats 31 and 38 by screwing member 29 to piston rod I 9. As an alternate form of construction, the screwthread connection between piston rod I8 and member 29 may be omitted and the rod and member made as an integral unit.

The syringe of the invention is simply and easily assembled as will now be prescribed. 'I'he piston rod I8 with the ring 26 connected thereto is inserted through the opening I 1 of the metallic cap I9, thumb pressure being exerted at 23 on the lever 22 to permit the piston rod to freely slide over brake rod 29. Spring seat 31 is now placed over piston rod I8 and moved to a position abutting the cap member I S as shown in Figure 2. The spring seat 38 is now placed over member 29 so as to abut the pin 34. A compression spring is now placed over the piston rod I3, its left end abutting spring seat 31 and its right end abutting spring seat 38. Member 29 is secured to the piston rod I8 and places the spring 39 under a slight initial compression. 'I'he piston 3| is now screwed on to the member 29 and the complete assembly is inserted into the glass barrel of the syringe. The assembly is completed by means of a threaded barrel 40 connecting cap IB to a threaded sleeve 4I which bears against a resilient washer 4I about the annular flange I2 of the glass barrel I D. The threaded sleeve 5I is provided with a projecting lug 42 to act as a iinger piece to facilitate the connection referred to.

Where piston rod I8 and member 29 are provided as an integral unit, assembly of the parts is accomplished by rst removing the metallic ring 29 from the end of rod I8 after loosening lock nut 21 and removing same. Rod I8 is now threaded through the right end of the spring assembly shown in Figure '1 and through opening I1 in cap I6. With spring 39 in compression, thumb pressure on 23, which is employed during the introduction of rod I8 through opening I1, is released and ring 26 is screwed to the left end of rod I9 and held there by lock nut 21.

In Figure 7a, I have disclosed the manner in which the tension spring is secured to the piston rod I8 and to the metallic cap I5. As viewed in this ligure the left end of the tension spring 39', which is considerably shorter than the compression spring 39, is secured to the cap I5 by being passed through the eyelets 3E. As the ends of tension springs are smaller in diameter than the balance of their length, the right end of the tension spring 39' will hook over and be retained by washer 33 which bears against the pin 34.

A further embodiment of the invention making use of the identical spring seating means disclosed in Figure 7a, contemplates the provision of a single spring actuating means which may have a combined tension and compression effect, thus obviating the necessity for changing springs from one type to another. The use of such a combination spring will reduce the capacity of the syringe by one-half but as this invention may be manufactured in any desired size this is a highly desirable feature of the invention. In using a spring means of this combination type, piston 3| will have a position exactly intermediate the length of the glass barrel I!! when the spring is at rest, that is, when in the intermediate position neither compression nor tension forces will be exerted upon the spring seats. It is obvious that when the syringe is used for injecting or aspirating uids, it will be cocked for operation against the action of the combination spring in the manner described in connection with the use in the syringe of a compression or a tension spring respectively.

The operation of the apparatus shown in Figures l to '7 inclusive, is as follows:

When it is desired to use the hypodermic syringe for supplying fluids under pressure for injections, a compression type spring is used and the syringe is assembled as hereinbefore described. The syringe is now cocked by depressing brake control lever 22 yby thumb pressure at 23 thus releasing the pressure of brake rod against the piston rod i8 and, as viewed in Figure 2, the piston rod is drawn to the left by means of ring 26 against the tension of the spring 39 While the needle of the syringe is held immersed in the iiuid which is to be injected. The thumb pressure is then re-leased and the brake rod 2G holds the piston rod I8 cocked and ready for use. A subsequent depression of thumb piece 23 will of course rotate brake rod 20 permitting piston rod I8 to move to the right under the action of compression spring 39 thus injecting the fluid as desired. Due to the length of the lever arm 22 very sensitivecontrol is provided thus permitting the rate of injection or the amount thereof to be extremely accurately controlled as a slight depression of the lever arm effects a slight decrease in pressure of brake rod 20 against piston rod I8. It is obvious that the injection may be stopped at any time desired and resumed at any subsequent time, and as the tight t of the piston 3l will prevent any leakage of the fluid no valves are required. Further, since rod I8 is held motionless by the brake, spring pressure is removed from the piston and thus, between injections, no pressure exists Within the barrel of the syringe which might cause leakage past the piston.

When the syringe is used for aspirating iiuid, a short tension spring (Figure 7a) is provided and in its initial released position the piston rod I8 and handle 26 (as viewed in Figure 2) will be positioned to the left as previously described, with the piston 3| also at the left lportion of the barrel. The syringe is now cocked by depressing thumb `portion 23 so as to release brake rod iii and permit piston rod I8 to be moved freely toward the right against the tension of the spring, and when the piston 3I reaches a position corr-csponding to the position shown in Figure 2, thumb pressure on member 23 is released and the brake rod 23 will lock the piston rod in this position. The needle is now inserted in a Vein, etc., from which fluid is to be aspirated and upon the release, or partial release, of the brake by thumb pressure upon the member 23, the piston 3i due to the tension of the spring, will move to the left to aspirate or draw in by suction the desired iiuid.

It is now apparent that I have provided a hypodermic syringe in which the piston is spring actuated to discharge or aspirate any desired iiuid and. which has a novel control means which will regulate with great accuracy the speed, or pressure with which the automatic injecting or aspirating action takes place. This novel control means or braking mechanism is simple, rugged and fool-proof in its construction and permits, due to the length of its control arm 22, minute graduations of pressure by brake rod 20 upon the piston rod I8 which is invaluable in the type of work for which syringes of this nature are used.

It is well known that movement of the syringe axially in either direction during an injection, etc., generally results in the displacement of the needle thereof or in pain and discomfort to the patient being treated. An important feature of this invention resides in the fact that the sensitive braking mechanism `provided can have no tendency to move the syringe in an axial direction as a result of the operation thereof. This important advantage is obtained by providing that pressure on the member 23 must be exerted in a direction transverse to the axis of the syringe, thus obviating any possibility that displacement of the needle can occur thru any fault but that of the operator of the syringe.

In Figures 8 and 9, I have shown a modification of the braking mechanism previously described. In this showing I have provided the metallic cap I6 with two brake rods 44 and d5 which are adapted to have a braking action against piston rod I3. These brake rods 44 and 45 are identical with either structure of bra-ke rod 2li as described and resul-t in a greater braking action on the piston rod I8 and serve to increase the life of the brake rods 44 and 45. The control lever 22 is provided at its rigid ccnnection with brake rod M with a gear segment 4G which is integral with lever 22, and the teeth of gear segment IIS mesh With the teeth of a similar gear segment i1 rigidly mounted on the brake rod B5. It will be apparent that pressure on the member 23 of control lever 22 against the action of a spring 48 mounted on cap I6, vfiil cause the brake rod d and accordingly brake rod 45 to pivot in cap member I6 to release the brake pressure exerted by both brake rods on piston rod I8. It is obvious that the advantages secured by the braking mechanism previously described apply doubly so in connection with this modification,v the braking action being equally and oppositely applied against opposite sides of the rod 20.

In Figures l0, 1l and 12, I have shown an additional modification of the invention. The threaded barrel 4B has formed integral therewith a hollow spindle or chuck 9 having a split tapered end so as to form a plurality of resilient jaws 5B. The cap member I6, as clearly shown in Figure l2, has formed therein :t flared opening 5I adapted to cooperate with the jaws 5U of the chuck is. When the cap I is rotated in a clockwise direction with respect to sleeve 4B, the jaws 5l? will move into the opening 5I and will be urged by the sides of opening 5I against the piston rod I8 to grip the same and accordingly furnish a very positive braking action thereon.

In order that relative rotation of cap I6 with respect to threaded sleeve iii may be more easily effected to result in a braking action on the piston rod I 8, an arm 53 is suitably secured to cap I6 and a second arm 54 is suitably secured to sleeve member 13B. A compression spring 55 is suitably secured to and mounted between the arms 53 and 55. It will at once become obvious that while the syringe including cylindrical sleeve i5 is being held by one hand and thus prevented from rotation, thumb pressure on the lever 53 against the action of compression spring 55 will eiect relative rotation of the cap I6 and sleeve 4i] thus backing off cap member I8 with respect to sleeve it to diminish the pressure of the sides of the opening 5I on the jaws 50, thereby diminishing the braking grip of the jaws and permitting brake rod I 8 to slide therethrough under the action of spring 38. It will be noted that this modication also includes the advantages hereinbefore described and especially the feature mentioned of a control lever having a long moment arm and upon which a pressure which is transverse to the axis of the syringe is exerted to effect the release of the chuck or brake means.

An additional modification of the invention is disclosed in Figure 13 which is similar in most respects to the modification shown in Figures 10 to 12 with the exception that a double chuck 57 is provided within the chamber formed by the sides of flared opening 5I in the cap I6 and by the sides of a similar opening 58 in sleeve 48, and the chuck cooperates therewith so that upon relative rotation of the cap I6 and the sleeve 48 in a clockwise direction (if cap IG is provided with right hand screw-threads) a double gripping or braking eiect on the piston rod I8 is eiiected by jaws 50 of the chuck 51 due to the pressure thereon by cap I6 and sleeve 48.

A 'further modilication of the invention is disclosed in Figures 14, l5 and 16. In this showing, the cap IG has provided therein, in addition to its centrally located opening I'I, an opening 68 through which a small shaft 5I projects for a purpose to be described, Cylindrical sleeve member 48 has an irregularly shaped opening 62 provided in its end (Figure 16; this opening being closed by the cap I5 (Figure 14). Two brake members 63 and 64 are pivotally connected to each other and to the cap I6 as at 65 and are so shaped as to nt snugly about piston rod I8. The upper ends of the members 63 and S4 are resiliently urged together by means of a tension spring 65. Moimted n shaft 6I is an eccentric 61 which, in the position shown in Figure 16, is in its brake releasing position, that is, is forcing the members 53 and 64 apart against the action of spring 56 and away from piston rod I8. A brake controlling lever 68 having a thumb portion 69 is rigidly secured to the other end of shaft 6I and is strongly urged to a full braking position by a leaf spring I8 mounted on the sleeve d,

It is apparent that thumb pressure at 69 on the control lever 63 against the action of spring l@ will cause ciockwise rotation of the shaft 6I and the eccentric 6'! to force bra-ke members 63 and 64 away from piston rod I 8 against the action of spring G as shown in Figure 16. It will again be noted that all the advantages hereinbefore described and relating to the control means will also apply to the present modification, the pressure exerted on 69 to eiect release of the brake members G3 and 54 also being in a direction transverse to the axis of the syringe.

mother modification of the invention is disclosed in Figures 17 and 18. In this showing the modication the piston opening I'I through the cap I6 is iiattened on one side as at 1I, the cap I6 being screw-threaded on sleeve 48 and having its opening I7 aligned with the opening through the sleeve. Piston rod I8 is provided with a at side as at 'I2 and at spaced intervals throughout its length with annular notches 73 extending thereabout except on the attened portion '12. The usual spring 39 is connected to the piston rod I8 as at I4 and to the inner face of sleeve 4D as at '15.

It is obvious that if the piston rod I B is to move axially through cap I5 and sleeve 48 its at side I2 must be turned so as to be aligned with the flat side 'II of the cap plate I6. Thus if the D- shaped piston rod I8 is turned so as to be aligned with the D-shaped opening II of cap I6 the piston rod I8 may then be drawn to the left as seen in Figure 17 against the action of spring 39 so as to cock the springs, the cocked position being retained by rotating rod I 8 out of alignment with the D-shaper opening of cap I6 so that the sides of any notch 'I3 will abut the flat side 'II of opening I 7. The position in which the D- shapedrpiston rod is out of alignment with the D-shaped opening II of cap I6 is the "at rest" position of the spring with respect to rotary motion between the piston rod I8 and the sleeve 48. It will thus be obvious that rotation of the rod I8 to alignment with opening II will place the spring 35 under torsion so that upon the sliding of the piston rod I 3 through cap I5 and sleeve 48 and the arrival of the next succeeding notch 73 at the opening I 'I of cap I5, this torsional force will act to rotate the piston rod I 8 back to its at rest position at which time the sides of the notches 73 will abut the iiat sideII of cap plate I 5 to prevent further axial movement of the piston rod.

It will be obvious that in the modication just described an extremely simple and eicient automatic syringe is provided for injecting or aspirating fluid in predetermined amounts, the amount of fluid to be injected or aspirated being determined by the spacing of the annular notches formed in the piston rod I8 and by the size of the syringe barrel used. If desired the cap IB may be arranged to rotate against suitable spring pressure with respect to sleeve '48 thus eliminating the need for rotating piston rod I8, the action of the several parts with respect to each other effecting the same braking action as just described.

Another modiiication of the invention is disclosed in Figures 19, 20, 21, 22 and 23. In this rod I8 is provided on its lower surface with teeth I'I and 'I3 of different lengths for a purpose to be described, these teeth being formed by notches or serrations to a predetermined depth. In milling or machining the projecting teeth are cut to specic heights with the exception of every fourth tooth which is left of greater height for a purpose to be described.

The sleeve l0 (Figure 21) is provided with an axially extending vertical slot I8 in its upper surface in which a brake lever is mounted for oscillation by means of pin 8l. The lower end of brake lever Sil is provided with an opening 83 extending therethrough and with an arcuate brake surface 82 adapted to bear on piston rod I8. Suitable resilient means such as a leaf spring 84 is secured to sleeve 4I) and has one end arranged to urge brake lever 85 upwardly thus forcing brake surface B2 downwardly against piston rod I8 to eect a braking action thereon. It will be noted that the brake lever as constructed and arranged has a long moment arm and consequently provides highly sensitive operation when releasing the pressure of brake surface 82 from piston rod I8 by manually exerting pressure on the upper end of the brake lever 8| in a direction transverse to the axis of the syringe.

In order to provide an even more sensitive brake controlling means, the upper end of brake lever 80 may have suitably mounted therein a screw adjustment consisting of a screw 85 mounted in a screw threaded opening 86 in the upper side of sleeve 40. Screw 85 is provided with an enlarged and knurled head 8l and it is apparent that by rotating knurled head 8l in either direction minute graduations of the braking effect by braking surface 82 on piston rod I8 may be obtained. The provision of the screw adjustment in brake lever 8| prevents normal manual depression thereof to effect a release of the brake.

The sleeve d is provided with a transverse slot or open-ing 8l extending therethrough (Figures 19, 2l and 22) in which is mounted a Dshaped plate 88 having lugs 89 and 90 for a purpose to be described. This plate 88 is pivotally connected at 8| to sleeve It and is provided with a rectangular opening 52 in order that piston rod I8 may pass freely therethrough. As seen in Figure 19 the other end of leaf spring 841 projects through the opening 83 in the lower end of brake lever 88 and bears upwardly against the lower edge of upper cross member 93 of D-shaped plate 88. It is apparent that the lower cross arm 94 is urged upwardly against or between the teeth TI and 'i8 by the pressure of leaf spring 8i against cross member 03 to thus prevent axial movement of piston rod i8. In order that the piston rod I8 may be prevented from rotating under the influence of the compression spring 39, a spline groove 95 is provided in a side face of the rod. A screw 9S extends diametrically through the sleeve itil and into the spline groove 95, permitting axial movement but not rotation of piston rod I8.

A longitudinal opening Idil (Figure 22) extending into the slot or opening 8l is drilled in the sleeve E0, terminating at its other end in a radial opening I8I in the side of the sleeve 40. Mounted for sliding movement in this opening |88 is a pin |02 having an operating lug or handle ISS. Suitable resilient means may be connected to the lug |03 of pin |82 to urge it into the opening 8l adjacent the lugs 89 and 88 on plate 88.

The pin |02 acts as a stop for the lugs 80, 88 and SII on plate 8B in its motion about its pivot 9| and may be retracted by means of lug |83 (Figure 22) so as to permit the lugs on plate 88 to move freely. Referring to Figure 21, it will be seen that pin |02 abuts the top surface of lug 90 on plate 88 to hold lower cross arm SII locked in a position below the short teeth ll but not below the long teeth I8 so that the piston rod I8 is free to move axially until anyone of the long teeth 'i8 abuts the lower cross arm Sli. By depressing the lug |05, plate 88 will be pivoted downwardly until pin |82 abuts the lower surface of lug 89 thus moving lower cross arm Si beneath or out of the way of the long teeth 'i8 so as to again permit axial movement of the piston rod I8. As plate 88 is urged upwardly by leaf spring 84 upon release of pressure on lug |05 it will be seen that pin |02 will resume its former position abutting the upper surface of the lug 90 on plate 88 so that cross arm 95 will again be in the line of and act as a stop for the next succeeding long tooth 18.

'If desired, the pin |02 can be retracted and after fully depressing lug |05, the pin |82 may be released to now be in a position abutting the upper side of lug 89 on plate 88. This position will retain the lower cross arm 94 of D-shaped plate 88 below the line of the long teeth 'I8 and thus permit the operator to entirely control the injection or aspiration of fluid by means of the brake lever 88 alone.

When it is desired to inject or aspirate fluids in an amount represented by the distance between the short teeth ll or between a short tooth 'Il and the next adjacent long tooth I8, the pin |02 will be placed in a position to abut the upper surface of the lug 9i formed by the continuation of the lower cross arm 5i. In this position, the lower cross arm Sil abuts the lower surface of the piston rod I8, preventing motion thereof, but when lug |05 is depressed until pin |02 abuts the lower surface of lug 08, the piston rod I8 is free to move a distance of one small tooth 'il as the lower cross arm 94 also moves downwardly with lug |05 to clear a lower tooth TI, but is urged upwardly again in the next space adjoining that tooth by action of the leaf spring 84 -on the lower surface of upper cross arm 93 when lug |05 is released.

It is obvious that any desired graduations or variations of amounts of fluid represented by the spacing Aof the teeth l1 and 'I8 could be arranged as desired. In the drawings, for purposesA of illustration, every'fourth tooth is shown as a long tooth 78 so that as desired, a cubic centimeter of fluid could be injected or aspirated by permitting the piston rod to move the distance between two long teeth 18, or only a quarter cubic centimeter could be delivered by permitting the piston rod to move only the distance between two small teeth l1.

When it is desired to operate the modification just described, the syringe is cocked and filled with fluid as described. If it is desired to deliver, for example, a cubic centimeter of uid the pin |02 is placed between the notches 8S and 98 as shown in Figure 21. The operator now depresses lug |05 permitting the large tooth 78 which is abutting lower cross arm 9i to pass thereover as the piston rod moves axially under the influence of the spring 39, the brake lever having been depressed manually or released by rotation of the knurled screwhead 85. Lug |05 is now released and leaf spring 80 urges the plate 88 upwardly so that the upper surface of lug 00 now abuts the pin |02 thus placing the lower cross arm Si in the path .of the next large tooth 'I8 to act as a stop therefor.

When it is desired to deliver only one-quarter of a cubic centimeter of fluid the pin |02 is inserted between lugs Q0 and 94 and operation is effected in the manner described above. As herenbefore mentioned, it is possible to entirely eliminate Ithe automatic stop action of plate 88 by placing the pin |82 so as to abut the upper surface of lug 89 which will hold the lower cross arm 91| of the stop plate 88 completely out of engagement with any of the teeth on the lower surface of the piston rod I8. It is obvious that the delivery of the predetermined. amounts of iiuid may be continued until the supply of fluid contained in the syringe is exhausted. Further the advantages of a long moment arm resulting in an extremely sensitive brake control is embodied in the present modification as well as in those modications previously described.

The provision of the adjusting screw S5 on brake lever 80 makes possible a very accurate control of uid delivery so that, it is possible to deliver deflnite amounts of fluid per uni-t of time successively until the fluid capacity of the barrel is exhausted, the piston stopping automatically upon delivery of each predetermined amount.

It will now be seen that in the description of the invention and its several modifications I have disclosed a novel and eflicient brake controlled automatic hypodermic syringe for use in the injection or aspiration of iiuids. The provision in this brake control means of a control lever having a substantial moment arm which is adapted to be actuated by manual pressure in a direction transverse to the axis of the syringe, results in a control means unexcelled with respect to its accuracy in use.

Further, the control means provided assures the definite delivery of any desired amount of fluid under the action of the spring due to the sensitivity of the control lever as combined with the positive braking elements of the invention. The provision of the syringe having a brake release means effected by transverse pressure which has no tendency to displace the needle of the hypodermic syringe during actuation thereof is of extreme importance in the medical and allied professions.

The combination of the control means described with the automatic stop means provided to arrest the motion of the piston upon the delivery of predetermined amounts of iluid is an important contribution to the art. The operator of a syringe constructed in accordance with the principles set forth, may inject or aspirate uids in predetermined amounts or at will successively or continuously, and with extreme accuracy and great facility.

Where the term barrel assembly is employed in the claims it is understood that this expression is not limited to the barrel per se but is intended to define those structural elements necessary to the completion of the assembly for holding uid. For example, the expression barrel assembly, as applied to the form of the invention in Figures 1 and 2, would include the barrel l0, sleeve 4l, tube 40, and cap 6.

It is to be understood that the forms of my invention herewith shown and described are to be taken as preferred examples of the same and that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims.

I claim:

1. In a syringe of the type described comprising a barrel assembly, a piston and piston rod therein, and spring means between said piston and said barrel assembly; brake means carried by said barrel assembly and mounted to turn on a xed axis and engaging said piston rod, controlling means connected to said brake means to effect a release thereof by motion transverse to the axis of said syringe, and resilient means separate from said brake means acting to return said controlling means to braking position.

2. In a syringe of the type described -comprising a barrel assembly, a piston and piston rod therein and spring means between said piston and said barrel assembly; brake means carried by said barrel assembly and comprising a lever pivoted on said barrel assembly, said lever having one end constructed and arranged to bear against said piston rod whereby pressure on the other end of said lever in a direction transverse to the axis of said syringe effects release of said brake.

3. In a syringe of the type described comprising a barrel assembly, a piston and piston rod therein and spring means between said piston and said barrel assembly; brake means carried by said barrel assembly and mounted to turn on a fixed axis and engaging said piston rod, controlling means fixed with respect to said brake means to effect a release thereof by motion transverse to the axis of said syringe, and resilient means separate from said brake means acting to return said controlling means to braking position.

4. In a syringe of the type described comprising a barrel assembly including a cap, a piston and piston rod in said barrel assembly, and spring means between said piston and said cap; brake means mounted in said cap to turn on a fixed axis and engaging against said piston rod, and controlling means constructed and arranged to effect release of said brake means from said piston rod, said brake means comprising an eccentric shaft.

5. In a hypodermic syringe of the type described comprising a barrel assembly including a cap, a piston and piston rod mounted vin said barrel assembly, and spring means between said cap and said piston; brake means comprising a rotatable rod mounted in said cap and having a notch cut therein to engage and brake said piston rod, controlling means connected to said rod, and resilient means acting on said controlling means to rotate the portion of the rotatable rod to braking position against said piston rod.

6. A hypoderimic syringe comprising a barrel assembly, a piston and piston rod mounted therein, said barrel assembly including a cap having an opening therein, a pin extending through said piston rod, spring seating means abutting said cap and said pin and mounted on said piston rod, spring means engaging said spring seating means, brake means mounted in said cap and engaging said piston rod, controlling means constructed and arranged to release said brake means and release said piston for movement by said spring means, and means separate from said brake means biasing said controlling means to brake-applying position.

7. A hypodermic syringe for injecting and aspirating fluids comprising a barrel assembly, a piston and piston rod mounted therein, said barrel assembly including a cap, a pin extending through said piston rod, spring seating means within said barrel assembly, spring means having its ends respectively engaging said spring seating means, brake means mounted in said cap and engaging said piston rod, controlling means constructed and arranged to release said brake means and release said piston for movement by said spring means to inject or aspirate said fluid, and means separate from said brake means biasing said controlling means to brake-applying position.

8. A hypodermic syringe comprising a barrel assembly, a piston and piston rod mounted therein, said barrel assembly including a cap having an opening therein, a pin extending through said piston rod, spring seating means within said barrel assembly, spring means engaging said spring seating means, brake means mounted in said cap against said piston rod, and controlling means constructed and arranged to release said brake means and release said piston for movement by said spring means.

9. A hypodermic syringe comprising a barrel assembly, a piston and piston rod mounted there- Vin, said barrel assembly including a cap having a flared opening therethrough, spring means between said piston and said barrel assembly, and means cooperating with the sides of the flared opening of said cap to form a chuck for engaging and braking said piston rod.

10. In a syringe of the type described comprising a barrel assembly, a piston and piston rod therein, and spring means between said piston and said barrel assembly, brake means for said piston and saidA piston rod carried by said barrel assembly, controlling means connected to said brake means to eiect a release thereof by motion transverse to the axis of said syringe, and automatic stop means to arrest motion of said piston and piston rod upon completion of a predetermined movement thereof.

BEVERLY DOUGLAS. 

